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  #21  
Old 08-15-2019, 06:37 PM
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ps7256 ps7256 is offline
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Which Amp did you buy?
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  #22  
Old 08-24-2019, 04:12 AM
Jim B Jim B is offline
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Default Ma252

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Originally Posted by ps7256 View Post
Which Amp did you buy?
Hi, as the thread says this is about the McIntosh Ma 252

I changes the tubes, no improvement there. Also return amp for another. That one also has same exact hum as previous, and as original poster.

I guess they all just hum.....
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  #23  
Old 08-07-2021, 09:52 AM
cheater cheater is offline
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I am surprised McIntosh do not use DC power for the heater elements - that eliminates heater hum entirely. It's been done for over 50 years now. Might be an inexpensive fix for everyone with the hum issue. Send it to a guitar amplifier technician who knows how to rebuild tube amplifiers, and tell him to add a DC tube heater supply. It's a three hour job at most.
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  #24  
Old 08-15-2021, 05:02 PM
AudioFi AudioFi is offline
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Hello buddy, I have been in your shoes, that Ma252 Hum, cost me thousands of dollars, I blamed the AC of my Home, cables, tubes and Power conditioner. Long story short, I used the refund of the MA252 to buy a MA8900 and I have been super happy with it for more than a year now...

It's a pity that the MA252 has that problem, it´s a very good sounding integrated for the price, but that hum is a complete design and quality flaw. For what I was told, the problem is in the power transformer.

This experience ended with better sound, the new integrated, a pair of super expensive 12ax7´s and 12aT7´s (those sounded amazing installed in the Ma252, but the hum was still there), new speaker cables, a lot of new things learned in the forums when trying to do some troubleshooting and an emptier wallet.

P.S. If you ever know of a good audio product that can take profit of those NOS 12ax7 and 12aT7 tubes, just let me know... I still in love with them and it's sad to see them stored in a box.
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  #25  
Old 08-15-2021, 05:10 PM
AudioFi AudioFi is offline
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Default very interesting

Quote:
Originally Posted by cheater View Post
I am surprised McIntosh do not use DC power for the heater elements - that eliminates heater hum entirely. It's been done for over 50 years now. Might be an inexpensive fix for everyone with the hum issue. Send it to a guitar amplifier technician who knows how to rebuild tube amplifiers, and tell him to add a DC tube heater supply. It's a three hour job at most.
Is your MA252 dead quiet after this fix?. How does it work when using headphones?. I remember that the hum was even more noticeable when using HP.
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